Various cyclic ethers such as tetrahydrofuran, tetrahydropyran, 1,4-dioxane, 1,3-dioxane, 2-methyl-1,3-dioxolane, etc. which are generated as chemical by-products or have been used as industrial solvents, are recognized as constituting environmental problems, particularly because of their toxicity and/or carcinogenicity.
Chemical methods of degrading dioxane using hydrogen peroxide and ozone in the presence of ultraviolet radiation currently are in operation but suffer from high cost.
While biodegradation has been reported for tetrahydrofuran, diethers having the cyclic dioxane type of structure have proven to be remarkably refractory to biological degradation and generally are considered not to be readily biodegradable. Degradation of dioxane has occasionally been reported but only in the presence of a cometabolite. No bacterial microorganism appears to be known which can use dioxane as its sole carbon source for growth.
Battersby et al., Appl. Environ. Microbiol., 55, 433-439 (1989) reported on the anaerobic biodegradation of 77 organic compounds and found little degradation potential for furan and tetrahydrofuran.
In an examination of 37 pollutants in industrial wastewater of a petrochemical plant utilizing activated sludge, Matsui et al., Wat. Sci. Tech., 20, No. 10, 201-210 (1988), found 4,4-dimethyl-l,3-dioxane was not biodegradable.
Burback et al., Appl. Environ. Microbiol., 59, 1025-1029 (1993) report that less than 50% of dioxane was degraded by Mycobacterium vaccae. Dioxane did not support the growth of this organism.
Because of the biorefractory behavior of 1,4-dioxane and 2-methyl-1,3-dioxolane, Adams et al., American Chemical Society Preprint Extended Abstract, I&EC Special Symposium, Atlanta GA, 485-488 (1993) employed a chemical oxidative pretreatment to enhance biodegradability.
Of six strains of Rhodococcus identified by Bernhardt et al., Appl. Microbio. Biotechnol., 36, 120-123 (1991) as having the ability to degrade tetrahydrofuran, only two were found to degrade dioxane. Despite considerable efforts, no strain was isolated or enriched when dioxane (or cyclohexane) was used as the carbon source.